基于数据集约束的并行数据流建模与描述研究

为了简化带有数据集约束的抽象网格工作流语言(AGWL)的工作流建立过程,提出了一种基于扩展面向对象Petri网(DOPN)建模并行数据流的方法.研究了AGWL并行数据流的特点,在此基础上对面向对象Petri网进行扩展,设计了基于扩展面向对象Petri网描述的并行数据流模型,之后定义一套从DOPN到AGWL的映射规则.最后通过一个应用实例对一个带有数据集约束的数据流建立DOPN描述,并生成AGWL数据流代码.该方法简化了AGWL工作流建立过程,并保留了流程验证和仿真的扩展性.     

面向对象双变迁Petri网及应用研究

针对Petri网数据流描述能力的不足,引入了数据变迁的概念,给出了双变迁Petri网的定义和图形表示,详细分析了双变迁Petri网的行为规则;定义了面向对象双变迁Petri网,使复杂系统的网模型易于分析理解;实例建模表明,该方法对控制流和数据流共存的复杂系统建模十分有效.     

Web服务组合的层次颜色Petri网描述模型

针对Web服务组合流程资源的表达及组合流程正确性验证问题,提出一个基于层次颜色Petri网的Web服务组合描述模型,该模型在描述组合流程控制流的同时还能描述流程中的数据流,能较全面地刻画Web服务组合流程,并且支持对组合流程正确性的验证分析、实例化流程的仿真运行。建模实例验证了该模型的有效性和实用性。     

基于GSPN的GERTS仿真模型研究

在分析维修设备保障流程建模与仿真重要性的基础上,分析了GERTS模型和广义Petri网(GSPN)模型在流程仿真中的应用特点,提出了基于嵌入式广义Petri资源约束网的GERTS仿真模型,并给出了具体的仿真算法.嵌入GSPN约束网的GERTS仿真模型,解决了GERTS难以对具有较强资源依赖性的过程很好描述的缺陷,可用于大型设备维修流程的仿真建模分析.最后,文章针对某部队对武器装备保障流程进行了建模和仿真实例分析,得出了资源配置的最优组合.并应用MATLAB对仿真结果进行了曲线拟合分析.     

基于扩展颜色Petri网的Web服务组合建模及应用

该文提出一个基于扩展颜色Petri网的Web服务组合描述模型,该模型在描述组合流程的控制流和数据流的同时还能描述流程中的参数、操作的语义和服务质量,能较全面地刻画Web服务组合流程;最后通过该建模方法给出一个建模实例。     

基于Petri网的海关业务流程工作流模型设计

现在人们大多都用Petri网进行工作流建模,但是传统Petri网的柔性和结构性不好,它会使图形变得庞大复杂难以理解.在时间Petri网的基础上引入了资源/变迁Petri网.这里通过对基于Petri网的海关业务流程工作流模型的实例分析可知,通过调整工作流程,最终可以得出优秀的工作流模型来优化工作流程、提高企业运行效率、增强企业竞争力,而且该建模方式也为设计与开发高可靠性、柔性和适用性的工作流模型提供很好的依据.     

应急预案流程的Petri网建模方法研究

为了提高应急信息系统模型的语义基础,提出了一种基于Petri网的应急预案流程的建模方法。以ABC模型为上位本体建立了应急预案流程本体,提出了应急预案流程的Petri网建模过程,并定义了应急预案流程中本体和层次Petri网的映射规则。使用该方法对某公路桥梁抢修应急预案流程进行Petri网建模,并通过仿真分析验证了建模方法的有效性。     

一种基于Petri网的工作流元模型研究

Petri网是建立离散系统模型有力的数学工具。为了解决基本Petri网建模能力不足的问题,Aalst提出了有代表性的WF-Net模型。提出的HSC-PN工作流元模型,基于WF-Net扩展,增加了模型元素静态属性、数据流全局共享和增强的活动块等特性。详细阐述了HSC-PN元模型的DTD文件规范,分析了该模型对工作流模式的支持、触发机制及验证方式。通过可视化的建模工具,生成符合DTD文件规约的流程模板XML文件表示。HSC-PN元模型具有更丰富的元素描述信息,简化了流程模型,具有更强的建模能力。     

基于Petri网的人力资源管理的模型设计

讨论了工作流管理系统中Petri网建模技术的基本特点,并利用Petri网建立了企业生产管理中人力资源管理的模型.该模型可作为工作流管理系统中的一个子模型,一旦企业的业务过程发生了变化,用户可通过面向对象的Petri网对业务过程的流程进行修改,修改后的流程将自动地应用在工作流管理系统中.此模型满足了企业建立特定资源模型的需要,实现了业务流程重组的要求,具有适用性和灵活性,为人力资源的自动化办公提供了方便.     

时间Petri网在即时检验流程建模中的应用

针对即时检验系统的设计与开发建模问题,提出一种基于时间Petri网的并发系统建模分析方法,为即时检验流程设计建立较为准确的信息化模型。通过将活动持续时间概念引入Petri网模型中,提出了适用于即时检验系统建模的时间Petri网建模方法,并设计了嵌入Petri网模型中的调度仿真器协助分析、优化即时检验控制过程。仿真实验结果表明所提出的时间Petri网建模方法在可达节点和运行时间等方面能够满足并行多类别即时检验调度与控制系统的流程建模实际需要,为流程仿真和分析提供有力工具,从而辅助系统设计者对即时检验系统进行优化。     

硬件描述语言Verilog的建模技术

通过对Verilog语言的导次化建模,门级建模,数据流级建模,行为建模,开关级建模等各个抽象层次的研究,全面阐述了Verilog的建模方法,对于理解,使用和制订我国的Verilog语言标准会有所帮助。     

面向数据流结构的指令映射优化方法

在高性能计算领域,数据流是一类重要的计算结构,也在很多实际场景表现出很好的性能和适用性。在数据流计算模式中,程序是以数据流图来表示的,数据流计算中一个关键的问题是如何将数据流图映射到多个执行单元上。通过分析现有数据流结构的指令映射方法及其不足,提出了基于数据流结构的新型指令映射优化方法。主要是根据多地址共享数据包的特性对指令映射方法进行优化,延迟多地址共享数据路由包的拆分,减少网络拥堵。     

Application of deterministic and stochastic Petri-Nets for performance modeling of NoC architectures

The design of appropriate communication architectures for complex Systems-on-Chip (SoC) is a challenging task. One promising alternative to solve these problems are Networks-on-Chip (NoCs). Recently, the application of deterministic and stochastic Petri-Nets (DSPNs) to model on-chip communication has been proven to be an attractive method to evaluate and explore different communication aspects. In this contribution the modeling of basic NoC communication scenarios featuring different processor cores, network topologies and communication schemes is presented. In order to provide a testbed for the verification of modeling results a state-of-the-art FPGA-platform has been utilized. This platform allows to instantiate a soft-core processor network which can be adapted in terms of communication network topologies and communication schemes. It will be shown that DSPN modeling yields good communication performance prediction results at low modeling effort. Different DSPN modeling aspects in terms of accuracy and computational effort are discussed.     

服务流程中的数据流处理

服务流程需要处理服务之间大量的异构数据的交互,不同的数据流处理方式直接影响了服务流程的执行效率。阐述了服务流程模型中的数据流表示模型、数据映射机制与数据流验证机制,论述了服务流程运行中的数据流调度、数据存储以及传输等数据管理问题,分析了数据流处理在服务流程中的应用情况。最后,结合现有的数据流研究进展,提出了数据流研究的展望。     

Modeling and optimizing large-scale data flows

Modern scientific collaborations require large-scale integration of various processes. Higher-level dataflow languages are used on top of parallel and distributed dataflow systems to enable faster data-intensive workflow programs development, their easier optimization, and more maintainable code. In this paper, we present the rationales, design, and application of the needed advanced support for modeling and optimizing data flows for data mining and integration processes. The optimization research and development is based on dataflow pre-execution modeling and extending the registry of process activities by advanced annotations. Additionally, the overall process from a dynamic model to a static model as input for the optimization algorithms is described. This novel approach is implemented within an advanced graphical user interface, called the Process Designer, in order to support semi-automatic optimization as well as within a dataflow execution platform, called the Gateway. It can be adapted to any dataflow language implementation. The Process Designer architecture based on modern (meta-)modeling concepts naturally supports validated transformations between external textual and internal graphical representations of the targeted dataflow language, and in this way significantly increases the productivity and robustness of the implementation processes.     

Software merge: Combining changes to decompositions

Computer aid for software evolution is needed for more effective software development, particularly in contexts where changes to large systems must be made rapidly. This paper addresses computer aid for the evolution of requirements models and high level software designs. We present an improved method for automatically merging changes to software designs expressed via annotated dataflow diagrams and hierarchical decomposition. This improvement addresses the structure of the design as well as the system behavior the design implies. We also present an improved method for automatically reporting and repairing conflicts between structural changes. These methods can be applied to the informal dataflow diagrams commonly used in requirements modeling and software design as well as to the more specific executable design representations used in the computer-aided prototyping system CAPS.     

Machine-Checkable Correctness Proofs for Intra-procedural Dataflow Analyses

This paper describes our experience using the interactive theorem prover Athena for proving the correctness of abstract interpretation-based dataflow analyses. For each analysis, our methodology requires the analysis designer to formally specify the property lattice, the transfer functions, and the desired modeling relation between the concrete program states and the results computed by the analysis. The goal of the correctness proof is to prove that the desired modeling relation holds. The proof allows the analysis clients to rely on the modeling relation for their own correctness. To reduce the complexity of the proofs, we separate the proof of each dataflow analysis into two parts: a generic part, proven once, independent of any specific analysis; and several analysis-specific conditions proven in Athena.     

Uniprocessor scheduling of real-time synchronous dataflow tasks

Real-Time Systems - The synchronous dataflow graph (SDFG) model is widely used today for modeling real-time applications in safety-critical application domains. Schedulability analysis techniques...     

PProto: An environment for prototyping parallel programs

This paper describes Parallel Proto (PProto), an integrated environment for constructing prototypes of parallel programs. Using functional and performance modeling of dataflow specifications, PProto assists in analysis of high-level software and hardware architectural tradeoffs. Facilities provided by PProto include a visual language and an editor for describing hierarchical dataflow graphs, a resource modeling tool for creating parallel architectures, mechanisms for mapping software components to hardware components, an interactive simulator for prototype interpretation, and a reuse capability. The simulator contains components for instrumenting, animating, debugging, and displaying results of functional and performance models. The Pproto environment is built on top of a substrate for managing user interfaces and database objects to provide consistent views of design objects across system tools.     

Dataflow architectures and multithreading

Contrary to initial expectations, implementing dataflow computers has presented a monumental challenge. Now, however, multithreading offers a viable alternative for building hybrid architectures that exploit parallelism. The eventual success of dataflow computers will depend on their programmability. Traditionally, they've been programmed in languages such as Id and SISAL (Streams and Iterations in a Single Assignment Language) that use functional semantics. These languages reveal high levels of concurrency and translate on to dataflow machines and conventional parallel machines via the Threaded Abstract Machine (TAM). However, because their syntax and semantics differ from the imperative counterparts such as Fortran and C, they have been slow to gain acceptance in the programming community. An alternative is to explore the use of established imperative languages to program dataflow machines. However, the difficulty will be analyzing data dependencies and extracting parallelism from source code that contains side effects. Therefore, more research is still needed to develop compilers for conventional languages that can produce parallel code comparable to that of parallel functional languages